[Migration] Update migration docs regarding claims related to supporting multiple emails and mobile numbers per user

[lashinijay]

Describe the issue:
With [1], the support for storing multiple emails and mobile numbers per user enabled. For that the following claims needs to be introduced for organizations.

http://wso2.org/claims/emailAddresses
http://wso2.org/claims/verifiedEmailAddresses
http://wso2.org/claims/mobileNumbers
http://wso2.org/claims/verifiedMobileNumbers

Related PRs

• Config changes to support multiple email addresses and mobile numbers per user carbon-identity-framework#5661

[1] - #19991